Variable incidence drive for deposition tooling

ABSTRACT

A coating apparatus, such as for vacuum deposition, in which an access port, of a deposition chamber, is provided with a hatch door having mounted on its inner surface workpiece supports adapted for turning on two mutually perpendicular axii within a stream of coating material. Included is a modification in which a plurality of supports are concentrically orbited about a third axis with the coating stream.

Brunner et al.

[ 1 VARIABLE INCIDENCE DRIVE FOR DEPOSITION TOOLING [75] Inventors: Rolf H. Brunner, Poughkeepsie;

William C. Lester, Hopewell Junction, both of NY.

[73] Assignee: International Business Machines Corporation, Armonk, NY.

122] Filed: May 31,1974

[21] Appl. No.1 475,005

[52] US. Cl ll8/49.I; 118/53 [51] Int. Cl. C230 13/08 [58] Field of Search ll8/5257, ll8/48-49.5, 500-503, 416; 117/107.]

[56] References Cited UNITED STATES PATENTS 1.003.441 9/1911 Eaton 118/238 X 2,369,155 2/1945 Marinsky ct a1 1 113/421 X 2,804.976 9/1957 Russcll et al 118/53 UX 1 1 June 17, 1975 2,824,029 2/1958 Zinty 118/53 UX 2.997.979 8/1961 Tassara... 118/49 3.046.157 7/1962 Nyman 118/53 UX 3,131,917 5/1964 Gessner ct a1. 118/59 X 3,236,205 2/1966 Kopito 1 l lit/49.1 3.297.475 1/1967 Flacchc t 118/53 X 3.673.984 7/1972 Coulombe... 118/416 3,752,691 8/1973 Little. Jr. 118/491 X Primary Examiner-Morris Kaplan Attorney, Agent, or FirmHenry Powers 7] ABSTRACT I Claim, 5 Drawing Figures VACUUM PUl lP PATENTEUJUN 17 I975 SHEET FIG. 3

VARIABLE INCIDENCE DRIVE FOR DEPOSITION TOOLING FIELD OF THE INVENTION This invention relates to deposition toolings, and more particularly, to providing rotational motion to substrates to be coated, such as semiconductor wafers or substrates, during coating operations to obtain better coverage over surface topography and more uniform coatings thereon.

BACKGROUND OF THE INVENTION Vacuum coating of substrates from a suitable source material is extensively used for various applications. Typically, such applications involve, among others, the deposition of non-metallic coatings on optical lenses, various coatings on paper, and in particular, the coating of electrically conductive metal and dielectric films on semiconductor substrates for enabling subsequent encapsulation and delineation of conductor patterns in semiconductor device fabrication.

Such systems comprise a deposition chamber under vacuum containing holders for the substrates to be coated within a coating stream generated by a spaced coating source also contained within the chamber. Alternately, such systems, as described in U.S. Pat. Nos. 3,5 24,426 and 3,641,973, can subdivide the deposition chamber into a coating chamber and a main or evaporation chamber, the latter containing a spaced source of coating material to be evaporated in a stream onto a substrate supported in the coating chamber which can controllably be placed in communication and isolation with respect to the evaporation chamber. A vac uum gate valve can be normally employed intermediate the coating and evaporation chambers to either, in the open position, place them in communication with each other or, in the closed position, to isolate each from the other. In any event, a vacuum source, such as a diffusion pump, is normally connected to the evaporation chamber to maintain a continuous vacuum therein.

Since the intensity in a cross-section of a stream of coating materia from a source thereof, varies in accordance with the cosine law of distribution, in order to prevent non-uniformity of deposition on substrates, particularly those with irregular surfaces, during coating operations, various arrang -rnents have proposed to subject the substrate to substantially the same amount of exposure in the coating stream. Some arrangements have proposed the pivoting of the substrates relative to the coating stream with simultaneous rotation thereof, to obtain optimized uniformity of the coating deposited across the surfaces of the wafer. Illustrative of the more simplified proposal are such as described in U.S. Pat. Nos. 2,351,537, 3,131,917, 3,297,475 and 3,756,847.

In order to further increase the uniformity of coating deposits, more complex arrangements for controlling the spatial disposition of substrates, in a coating stream, have been advanced. Such arrangements are typically designed with a fixture or rack adapted for rotation of each of a large number of substrates on an axis oblique to the coating stream with concurrent orbiting of the substrates about a second parallel axis, and rotation of the holders about and within the coating stream. Illustrative of these systems is that described in U.S. Pat. No. 3,598,083.

Each of such systems is characterized by substrate holding fixtures which are discretely mounted in a coating chamber requiring substantial disassembly of the coating apparatus for loading and unloading of workpieces, particularly where complex motion is desired for the substrates. Where simplified loading and unloading of workpieces is provided for, the substrate motions have been characterized with a corresponding simplicity.

SUMMARY OF THE INVENTION It has been discovered in accordance with this invention, that fixtures for imparting complex motion to substrates, during coating operations, can be made an integral part of the coating apparatus. In its simplest configuration, such a fixture can be mounted on a hatch or closure member pivotally mounted adjacent an access port of a coating chamber, which on sealing closure therewith position the substrate in a coating stream generated from a suitable source. In this configuration, the substrates can be angularly indexed or reciprocated in the coating stream on one axis with concurrent rotation of the substrates on a transverse or perpendicular axis. In the preferred form, for coating ofa plurality of substrates, the fixture can be provided with orbital motion of the substrates about an axis coextending with substrate rotational axis.

Other features, objects and advantages will become more apparent from the following more detailed description of the invention in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic drawing in cross-section of one embodiment of the complex motion drive in accordance with this invention.

FIG. 2 is a diagrammatic view of a substrate holder for use in the embodiment of FIG. 1.

FIG. 3 is a more detailed schematic drawing of the complex motion drive of FIG. 1.

FIG. 4 illustrates a spatial variability of the substrate holder in the drive of FIG. 3.

FIG. 5 is a schematic drawing of a more complex motion drive embodiment of this invention incorporating the feature of orbital motion.

DESCRIPTION OF PREFERRED EMBODIMENTS Although the vacuum coating apparatuses of this invention have a wide variety of applications, they will be described below in conjunction with the coating of electrically conductive metal films on semiconductor substrates for subsequent photolithographic delineation of conductor patterns in device fabrication.

Referring to the drawings, the vacuum coating apparatus 1 comprises a deposition chamber 2 in a vacuum environment generated by a vacuum pump 3 (e. g. a diffusion pump) through a vacuum access duct 4 in the lower wall of the chamber enclosure 5.

The deposition chamber 2 includes a conventional vapor or ion source 6 of the type shown in U.S. Pat. No. 3,710,072 which may be referred to for details of construction. Source 6 will normally comprise a water cooled crucible 7 having coolant passages 8 through which a coolant may be circulated by suitable means, not shown. Crucible 7 contains a molten pool 9 of evaporant material from which vapor of the coating is produced, as for example aluminum or copper aluminum alloy for coating of an electrically conductive film of semiconductor substrates 10 (see FIG. 2) in device fabrication. The molten pool 9 is heated by an electron beam 11, deflected in an arcuate path by suitable magnetic field, from an electron beam gun l2.

Mounted in deposition chamber 2, about vacuum source 6, is an enclosing evaporant shield 13 having an opening 14 in top wall 15 thereof, for shaping the evaporant stream 16 of the coating material from source 6.

In order to prevent the coating of drive fixture 17 in the closed position, a shutter 18 is provided between the source material 16, at the shaping port 14, and the drive fixture 17. The shutter 18 is mounted on a pivot shaft 19 extending through shield 15, the bottom wall 20 (of chamber 2) and in a vacuum tight bushing 21 secured thereto.

Deposition chamber 2 includes an access port 29 which serves to load and unload substrates into and out of the chamber. The access port 29 is adapted to be opened and closed by a hatch door or cover member 30 pivotally mounted to a bracket 31 and having an annular groove 32 for mounting of an O-ring 33 or other suitable sealing means.

Located on the inner surface of hatch 30 are frame members 36 and 36A for suspension of the drive fixture 17. The fixture 17 includes a substrate holder rotatably mounted by spindle 38 in a bearing 39 of yoke member 40 having one leg 41 secured to a pin 42 pivotally mounted through a bearing 43 in frame member 36. Mounted at the outboard end of pin 42 is a bevel gear 44 in driven relationship with a mating bevel gear 45 on a drive shaft 46 extending through hatch 30 for external drive by a suitable gear train and motor means, not shown, for pivoting the support fixture 17 in any angular displacement or in reciprocating motion of the substrate holder within the evaporant path stream 16. The angular displacement of the substrate holder 37 can be indexed or programmed to provide a corresponding fixed angle of incidence to the evaporant path 16, from horizontal to vertical; or the holder 17 can be reciprocated or oscillated to continuously vary the angle of incidence, during deposition, to optimize the coverage of complex geometry steps. In programmed pivoting of fixture 17, the holder 37 can be exercized through a series of sequential angles of incidence and wafer dwell times at the various angles.

Rotatably secured through a bearing 47 in the other leg 48 of yoke 40, is a shaft 49 also rotatably extending through the bearing 50 in frame member 36A. The outboard end of shaft 49 has secured to it a bevel gear 51 drivingly meshed with a mating bevel gear 52 on the end of a drive shaft 53 extending through hatch 30 for external rotational drive by a suitable motor means, not shown.

The inboard end of shaft 49 has secured to it a pulley 54 to drive the substrate holder 37 by means of a spring or elastic belt 55 which passes over idler pulley 56 and around driver pulley 57 secured to the end of spindle 38.

Holder 37 comprises a support base 58 having a plurality of finger grips 59 having pivoted clamping lips 60 positioned over the support face of base 58 by means of compression springs 61 which are secured between annular seats 62, secured to the back side of support base 58, and like registered annular seats 63 secured to lateral extensions 64, of grips 59, pivotally mounted to brackets 65, also secured to the back side of support base 58. As will be noted, the lips 60 are formed with an angular configuration 66 to facilitate camming of grips 59 open if a tool is desired to be employed for positioning substrate 10 on holder 37.

Mechanical movement of the closure hatch or lid 30 can be effected by pivotally connecting mounting bracket 31 to a clevis member 67 on the end of a piston rod 68 of a pneumatic or hydraulic cylinder 69 suitably mounted (not shown) in any convenient manner to the vacuum coating apparatus.

In operation, for loading of a substrate, hydraulic cylinder 69 can be activated to open hatch 30, with supplemental actuation of drive shaft 46 to pivot yoke 40 to the angular displacement necessary to position holder 37, in the horizontal position, particularly if mechanical means are employed for loading and unloading substrates. At this point, any substrates on holder 37 may be removed, and a new substrate (e.g. a semiconductor wafer) mounted thereon, followed by closure of hatch 30, which will position the substrate in the evaporant path 16 on rotation of shutter out of in front of the shaping port 18 to permit the evaporant stream from vacuum source 6 to flow onto the substrate 10 mounted on holder 37. To protect major portions of the drive fixture from undesired deposition of the coating material, a protective shield 70 is provided with an aperture 71 to restrict the deposition area of the evaporant stream 16 to substantially the substrate 10.

For the coating operation, the drive shaft 46 can be actuated to position the substrate 10 to the desired angular orientation in evaporant stream 16; or for oscillation or reciprocation of the substrate in the evaporant stream. For photolithographic delineation of conductor pattern on semiconductor devices, the vacuum source can comprise a molten pool of 70 aluminum/30 copper alloy to coat an electrically conductive metal film on the wafer (e.g. substrate 10).

FIG. 4 illustrates a modification of the complex motion fixture in this embodiment enabling vertical dis placement of the holder 58 along the extension of spindle 38. For this purpose, spindle 38 is bored to accommodate a stem 38A slideably secured within the spindle 38 by a set screw 72 after the spatial disposition of the holder 38 is obtained, as for example as shown in phantom in the drawing. As will be understood, the exterior end of stem 38A is secured to holder 37.

FIG. 5 shows another embodiment of this invention in which orbital motions are provided for substrate holders 37A. In this embodiment, the stems 38B of a plurality of holders 37A, are mounted through bearings 39A in a rotator stage 73, having a spindle 74 extending via bearings 75 and 75A through the cross-piece 76 of yoke 40A. Secured to the bottom of cross-piece 76 is a stationary sun gear 77 peripherally extending from hollow shank 78 mounted about spindle 74. The sun gear 77 is meshed with satellite gears 79 secured to the top of the holder stems 383. As can be seen, when the rotorstage 73 is rotated to orbit the holders about the axis of spindle 74, the satellite gears 79 are driven about sun gear 77 to induce rotation of the holders 37A about a parallel axis.

Drive for the rotor stage 73 is obtained by means of the driven pulley 80 via a belt drive 81 (e.g. a steel band) which passes over a drive pulley 82 mounted to drive spindle 83 which extends through bearings 84 and 84A, and has secured to its opposite end a bevel gear 85 meshed with a second bevel gear 86 secured to the end of the drive shaft 49A. By means of the foregoing tional axisof holders 37 and 37A, as well as the axis 1 rotor shaft 74 where orbital motion is included in the system.

While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and detail may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. Apparatus for coating a plurality of substantially planar substrates comprising A. a coating chamber;

B. a port in a wall of said chamber;

C. a hatch means pivotally mounted on said wall for movement into open and closed position relative to said port with said closed position securing said hatch in sealing relationship with said coating chamber; oscillatory frame means supported on the inner wall of said hatch means;

E. means supporting said frame additionally supporting means to oscillate said frame;

F. rotatable means supported within the said frame and mounting a plurality of substrate holders in a substantially common plane on a circle concentric with the axis of said rotatable means;

0. means rotating said rotatable means whereby to orbit said holders about said axis, said axis being normal to the axis of said oscillation;

H. rotary means carried on said rotatable means and operatively associated with said holders whereby to rotate each said holder about its own axis which is normal to the axis of said oscillation;

I. drive means common to each said rotary and rotatable means whereby to simultaneously effect said holder orbital and rotative movements;

J. said holder orbital and rotative and said frame oscillatory movements occurring simultaneously; and

K. coating means comprising a vapor source for evaporating and directing a stream of coating material onto said substrates. 

1. Apparatus for coating a plurality of substantially planar substrates comprising A. a coating chamber; B. a port in a wall of said chamber; C. a hatch means pivotally mounted on said wall for movement into open and closed position relative to said port with said closed position securing said hatch in sealing relationship with said coating chambeR; oscillatory frame means supported on the inner wall of said hatch means; E. means supporting said frame additionally supporting means to oscillate said frame; F. rotatable means supported within the said frame and mounting a plurality of substrate holders in a substantially common plane on a circle concentric with the axis of said rotatable means; G. means rotating said rotatable means whereby to orbit said holders about said axis, said axis being normal to the axis of said oscillation; H. rotary means carried on said rotatable means and operatively associated with said holders whereby to rotate each said holder about its own axis which is normal to the axis of said oscillation; I. drive means common to each said rotary and rotatable means whereby to simultaneously effect said holder orbital and rotative movements; J. said holder orbital and rotative and said frame oscillatory movements occurring simultaneously; and K. coating means comprising a vapor source for evaporating and directing a stream of coating material onto said substrates. 